I. Field of the Invention
The present invention relates generally to surgery and, more particularly, to directional dilation during intraoperative monitoring through the use of a stationary directional dilator.
II. Discussion of the Prior Art
Intraoperative monitoring is commonly employed during surgeries which involve passing surgical instruments near or through tissues or areas having neural structures which, if contacted, may result in neurological deficit for the patient. Spine surgery is but one example and may be employed to address any number of different spinal disorders. To do so, it is necessary to create an operative corridor extending between an incision site and the spinal column. Depending on the approach or trajectory to the spine (e.g. anterior, posterior, lateral, etc.), different tissues will need to be traversed in order to establish the operative corridor.
The XLIF® procedure by NuVasive, Inc. is an exemplary surgical procedure, which involves establishing an operative corridor from a lateral approach to the lumbar spine while traversing through the psoas muscle. The psoas muscle is known to contain nerve roots which exit from the spinal cord. To safely establish an operative corridor through the psoas muscle, NuVasive, Inc. has developed certain systems and methods, such as that shown and described in U.S. Pat. No. 7,905,840 (hereinafter “the '840 Patent”), the entire content of which is hereby expressly incorporated by reference into this disclosure as if set forth fully herein.
The '840 Patent includes an electromyographic (EMG) intraoperative monitoring system and an access system comprising sequential dilators and a split-blade retractor, which collectively provide the ability to establish a so-called “less invasive” or “minimally disruptive” operative corridor through the psoas muscle to a surgical target site in the lumbar spine. Each sequential dilator has an electrode at the distal end which, when coupled to the intraoperative monitoring system, provides the ability to send a stimulation signal into the surrounding tissue to help determine the presence of nerves. Each sequential dilator may be physically rotated about its longitudinal axis during such stimulation to help determine the direction of the nerve(s) relative to the electrode and thus the dilator. This nerve proximity and nerve direction information may be used by the surgeon to help inform his or her surgical decision-making.
The present invention presents an alternate manner of directional dilation during surgeries involving intraoperative monitoring, including but not limited to spine surgery.